Flip retrograde cutting instrument

ABSTRACT

A flip retrograde cutting instrument and method of retrograde drilling using such an instrument. A method of forming a socket includes providing a flip retrograde cutter, inserting the cutter into a joint with a blade of the cutter in a straight position, pivoting the blade to a non-straight flip position, locking the blade in the flip position, and retrograde drilling a socket using the blade in the flip position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 12/114,599,filed May 2, 2008, which claims priority to U.S. Provisional ApplicationNo. 60/915,607, filed on May 2, 2007, the disclosures of which arehereby incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to arthroscopic surgical methods andinstruments and, more specifically, to a flip retrograde cuttinginstrument and methods of retrograde repairs and reconstructions.

2. Description of the Related Art

During arthroscopic surgery, a small incision is made in the skincovering the arthroscopic site or joint, and a cannula is inserted inthe incision to provide a pathway for surgical instruments to be placedin the joint and manipulated through arthroscopic visualization.Surgical instruments inserted through cannulas must be long andthin—this presents limitations on instruments for cutting tissue, as thediameter of the cannula ordinarily limits the width of the cuttingimplement.

Retrograde drilling of sockets and tunnels for ACL reconstruction isknown and described, for example, in U.S. Patent Application PublicationNo. 2007/0233138, entitled “Method and Apparatus for ACL Reconstructionusing Retrograde Cutter”, the disclosure of which is incorporated byreference herein. In such a method, sockets in bone created byretrograde cutting. A rotary cutter, mounted onto an insertion post of aguide, is inserted through an anteromedial portal into the knee joint. Adrill pin is drilled through the tibia and advanced until it contactsand engages a cannulation in the rotary cutter on the guide. Furtherrotation of the drill pin disengages the rotary cutter from the guide.The retrograde drill pin is then retracted and simultaneously rotatedfor retrograde cutting of a socket or tunnel of desired depth in thetibia. A similar method can be used for drilling a femoral socket ortunnel. A need exists for a surgical cutting instrument that can be usedarthroscopically for retrograde drilling of tunnels or sockets in bonewithout requiring a rotary cutter and drill pin. As with allarthroscopic instruments, the surgical cutting instrument must beconfigured for insertion through a narrow cannula, but able to cut arelatively wide tunnel or socket.

A need also exists for a surgical cutter that is stable during kneearthroscopy and that provides drilling of femoral and tibial sockets ortunnels independently of one another and minimizes incisions of distalcortices and reduces intraarticular bone fragmentation of tunnel rims.

SUMMARY OF THE INVENTION

The present invention provides a flip retrograde cutter having a blade,preferably a flip blade, that is configured to articulate between atleast a first “straight” position, for example, substantially parallelto a longitudinal axis of the flip retrograde cutter, and at least asecond “flip” position, for example, a non-parallel position relative tothe longitudinal axis of the flip retrograde cutter.

The present invention provides a flip retrograde cutter that creates arecipient site socket from the inside out, i.e., using a retrogradetechnique, with minimal incisions of distal cortices and reducedintraarticular bone fragmentation of tunnel rims.

The flip retrograde cutter of the present invention may be employed in aretrograde manner, to form a recipient socket (to accommodate anosteochondral transplant, or to allow retrograde fixation of a graftwithin two sockets, for example). Formation of the recipient socketbegins by inserting the flip retrograde cutter in the “straight”configuration into the joint space, preferably from the outside in,through a small diameter tunnel. A locking tube of the instrument isthen retracted so that the blade can be articulated into the “flip”configuration, i.e., into a position other than the “straight” positionand preferably at about 90 degrees to the longitudinal axis of theinstrument. The device is locked in the “flip” position by tighteningthe locking tube. A socket is created by conducting a drillingoperation, i.e., by rotating the instrument, while the device is pulledoutwardly.

Other features and advantages of the invention will become apparent fromthe following description of the invention, which refers to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B illustrate perspective views of a flip retrograde cutter ofthe present invention showing the blade in straight and flip positions.

FIGS. 2A-2B illustrate an exploded view and a perspective view of theflip retrograde cutter of the present invention.

FIGS. 3A-3C illustrate various views of a driver end of the flipretrograde cutter of the present invention.

FIG. 4 illustrates a perspective view of a nut of the flip retrogradecutter of the present invention.

FIG. 5 illustrates a perspective view of a hub of the flip retrogradecutter of the present invention.

FIGS. 6A-6B illustrate various views of a locking tube of the flipretrograde cutter of the present invention.

FIG. 7 illustrates a perspective view of a blade/cutter tip of the flipretrograde cutter of the present invention.

FIGS. 8A-8B illustrate various views of a shaft of the flip retrogradecutter of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following detailed description, reference is made to variousspecific embodiments in which the invention may be practiced. Theseembodiments are described with sufficient detail to enable those skilledin the art to practice the invention, and it is to be understood thatother embodiments may be employed, and that structural and logicalchanges may be made without departing from the spirit or scope of thepresent invention.

Referring now to the drawings, where like elements are designated bylike reference numerals, FIGS. 1-8 illustrate various components of aflip retrograde cutter 100 of the present invention. The flip retrogradecutter 100 creates a recipient site socket from the inside out, i.e.,using a retrograde technique, with minimal incisions of distal corticesand reduced intraarticular bone fragmentation of tunnel rims.

The flip retrograde cutter 100 includes a cannulated elongated body 100c having a distal end 100 a and a proximal end 100 b, as shown inFIG. 1. The body 100 c of the flip retrograde cutter 100 includes ashaft 6 and a locking tube 4, with a blade 5 at the distal end 100 a ofthe instrument, as shown in FIGS. 2A-2B. The following is a list ofparts of the flip retrograde cutter 100: driver end 1, nut 2, hub 3,locking tube 4, blade/cutter tip 5, shaft 6, retainer ring 7, cross pin8, slotted spring pin 9, pin 10 and O-Ring 11. Details of the variousparts of the flip retrograde cutter 100 are illustrated in FIGS. 2-8 andlisted below in Table 1.

TABLE 1 Apparatus of the present invention Flip Retrograde CutterOverall dimensions: 13.58 inches (length) × 3.5 mm (shaft diameter)10.75 inches (length from hub to blade) Cutting diameter: 6-13 mm. Bladerotates freely and locks in straight and 90 degree positions. Driver EndOverall dimensions: 2.1 inches (length) × 0.156 inches (diameter ofunthreaded portion) Thread size: 1/4-20 UNC-2A (¼ inches diameter with20 threads/inch). The threads start 0.1 inch from one end. Unthreadedportion: 1.13 inches (length) with a through hole of 0.063 diameter at0.96 inch from one end. Material: 18-8 Stainless Steel; clean andelectropolish finish Nut Overall dimensions: 0.365 inches (innerdiameter of through hole) × 0.585 inches (width). Thread Size: 1/4-20UNC-2B Material: Polylac PA-747 Acrylonitrile butadiene styrene (ABS)Color: Blue Hub First Portion: 0.625 inches (outer diameter) × 0.383inches (height) × 2° slope between the diameters at both ends of thefirst portion. Second Portion: 0.979 inches (height) × 24° slope betweenthe diameters at both ends of the first portion. Material: PolylacPA-747 Acrylonitrile butadiene styrene (ABS) Color: Blue Locking TubeOverall dimensions: 0.134 inches (diameter) × 11.05 inches (length) Tubehas a slot on one end having a width of 0.04 inches and a length of0.175 inches from the end. Laser etch lines around circumference of thetube. Material: 17-7 Stainless Steel Condition A; clean andelectropolish finish. Blade Overall dimensions: 118° (tip angle) × 0.138inches (cutting radius) Effective cutting diameter: 6-13 mm Material:17-4 PH Stainless Steel; clean and electropolish finish Shaft Overalldimensions: 0.102 inches (diameter) × 11.625 inches (length). One end ofthe shaft has a through hole 0.15 inches from the end and having adiameter of 0.04 inches. Another end has a slot with a slot width of0.04 inches and a length of 0.175 inches from the end. The slotted endalso has a through hole having a diameter of 0.04 inches. Material: 17-4PH Stainless Steel; clean and electropolish finish. Retainer RingOverall dimensions: 0.475 inches (outer diameter) × 0.375 inches (innerdiameter) × 0.125 inches (slot gap) × 0.032 inches (thickness).Material: Polylac PA-747 Acrylonitrile Butadiene Styrene (ABS) Color:Blue Cross Pin Overall dimensions: 0.0396 inches (diameter) × 0.1 inches(length) Material: 18-8 Stainless Steel Slotted Spring Pin Overalldimensions: 1/16 inches (diameter) × ⅜ inches (length) Material: 18-8Stainless Steel Pin Overall dimensions: 1 mm × 4 mm Material: 18-8Stainless Steel O-Ring Overall dimensions: 0.25 inches (outer diameter)× 0.125 inches (inner diameter) Basic shape: Round in plan shapeMaterial: Viton Color: Black

The flip retrograde cutter 100 is preferably assembled by first pressingthe locking tube 4 into the hub 3 until the locking tube 4 bottoms out.The retainer ring 7 is then inserted into a groove 3 a of the hub 3 toform a first sub-assembly.

Next, the shaft 6 is slide into end 1 a of the driver end 1 and securelyengaged using the pin 10. The first sub-assembly, described above, isslide over the assembled shaft 6 and driver end 1. Next, the blade 5 isslide into slot 6 a of the shaft 6 and securely engaged using the crosspin 8, subsequently welding in place the cross pin 8 at both its ends.The nut 2 is then screwed onto end 1 b of the driver end 1. Next, thehub 3 is pulled back while advancing the nut 2 until the retainer ring 7engages and the slotted spring pin 9 is inserted into a through hole 1 cin the driver end 1 to secure the driver end 1 against the nut 2. TheO-Ring 11 is slide over the locking tube 4, having laser etches 4 a onits circumference, until the O-Ring 11 is about 3-5 inches from the hub3. The O-Ring 11 may be used to measure depth during retrogradedrilling.

Details of the blade 5 of the flip retrograde cutter 100 are illustratedin FIG. 7; however, the invention contemplates other shapes andgeometries for the blade 5. The blade 5 is configured to engage theshaft 6 and to articulate between at least first and second positions.In an exemplary embodiment, blade 5 engages shaft 6 in a first or“straight” position (FIG. 1A), for example, about parallel to thelongitudinal axis of the cutting instrument 100. The blade 5 alsoengages shaft 6 in a second or “flip” position (FIG. 1B), for example, anon-parallel position relative to the longitudinal axis of the cuttinginstrument 100, preferably about 90 degrees relative to the longitudinalaxis. The present invention, however, contemplates embodiments whereinthe blade 5 forms any angle with the shaft 6, for example, an anglebetween about 10 to about 170 degrees relative to the longitudinal axisof the cutting instrument 100.

In use, once the flip retrograde cutter 100 is inserted into a joint,for example, a knee joint, the surgeon rotates the nut 2 to allow thelocking tube 4 of the flip retrograde cutter 100 to retract. The blade 5is then articulated, for example by manipulating it with anotherinstrument, so that it is pivoted into the “flip” position, i.e., into aposition other than the “straight” position, preferably 90 degrees tothe longitudinal axis of the instrument. The surgeon may modify theangle of the blade, as desired and in accordance with thecharacteristics of the surgical site. Once the blade 5 is articulated inthe desired “flip” position, the blade 5 is preferably locked bytightening the locking tube 4. A drilling operation, for example, aretrodrilling step, may be subsequently carried, as known in the art.

According to an exemplary embodiment, the flip retrograde cutter 100 ofthe present invention may be employed in a retrograde manner to form arecipient socket (at the location of an osteochondral lesion developedon the head of the tibia, for example, or to accommodate retrogradefixation of a graft within two sockets). Formation of the recipientsocket begins by inserting the flip retrograde cutter 100 in the“straight” configuration into the joint space, preferably from theoutside in, through a small diameter tunnel (for example, of less thanabout 4 mm). The locking tube 4 of the instrument is then retracted andthe blade 5 is articulated into the “flip” configuration (i.e., into aposition other than the “straight” position). The “flip” position ispreferably locked by tightening the locking tube 4 to allow a drillingoperation to take place.

The present invention may be used to form various sockets or tunnels forgraft fixation or to create sockets in a retrograde manner forreplacement osteochondral cores or implants, obviating the need forinserting harvesters into the joint. For example, the flip retrogradecutting instrument 100 of the present invention may be employed for theformation of sockets during an “All-Inside ACL RetroConstruction”ligament repair, by drilling at least a femoral and tibial tunnel orsocket using a retrodrill technique employing the flip retrogradecutting instrument 100 of FIGS. 1-2. A graft (soft tissue graft or BTBgraft) may be provided in the vicinity of the sockets and the graftsecured within the femoral and tibial tunnels (sockets).

According to yet another embodiment, an exemplary method of ACLRetroConstruction of the present invention includes drilling a femoralsocket, and drilling a tibial tunnel or socket using a retrodrilltechnique employing the flip retrograde cutting instrument 100 of FIGS.1-2. Next, a graft (soft tissue graft or BTB graft) is provided in thevicinity of the sockets and the graft is secured to a continuousloop/button construct having a button with an oblong configuration andprovided with an inside eyelet that allows the passage of the continuousloop, preferably a suture loop. The graft is passed with the buttonthrough the femoral tunnel and the button is secured to the femoralcortex once the button exits the femoral socket. Finally, the graft issecured in the tibial tunnel or socket.

Although the above-detailed methods of socket formation using the flipretrograde cutter 100 of the present invention have been described withreference to a specific ACL reconstruction, i.e., a specific “all-insideACL RetroConstruction” for ligament repair, the invention is not limitedto this exemplary embodiment, and contemplates any repairs andreconstructions that employ a cutting instrument such as flip retrogradecutter 100 of the present invention.

Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. It ispreferred, therefore, that the present invention be limited not by thespecific disclosure herein, but only by the appended claims.

What is claimed is:
 1. A flip retrograde cutter comprising: a cannulatedelongated body having a distal end, a proximal end and a longitudinalaxis, the body further comprising a shaft; a blade at a distal end ofthe shaft, the blade being securely engaged to the shaft and capable ofmovement from a first position generally aligned with the longitudinalaxis of the body to a second, flip position which is not aligned withthe longitudinal axis; and a locking tube over the shaft, the lockingtube being configured to be retracted to allow the blade to articulateand to flip, the locking tube being further adapted to be tightened andto securely lock the blade in the second, flip position, the lockingtube having a slot at its distal end to securely lock the blade in agiven position, wherein the blade is articulated to an angle of about90° to the longitudinal axis of the shaft of the flip retrograde cutterwhen the blade is in the second, flip position, and wherein, in thesecond, flip position, the blade faces the proximal end of the body forretrograde drilling of a bone tunnel or socket when the flip retrogradecutter is pulled proximally.
 2. The flip retrograde cutter of claim 1,further comprising: a hub attached to a proximal end of the lockingtube; a driver end having screw threads in a portion near a distal endof the driver end and a cannula at the driver end's distal end, aproximal end of the shaft being inserted into the cannula; and a nut tosecurely engage the screw threads of the driver end and the hub.
 3. Theflip retrograde cutter of claim 2, further comprising an O-Ring, theO-Ring being placed over the locking tube, wherein the O-Ring is used tomeasure depth during retrograde drilling.
 4. The flip retrograde cutterof claim 2, wherein the locking tube is retracted by rotating the nut.5. The flip retrograde cutter of claim 1, wherein the blade has acutting diameter of about 6 mm to about 13 mm.
 6. The flip retrogradecutter of claim 1, wherein the shaft is made of stainless steel.
 7. Theflip retrograde cutter of claim 1, wherein the locking tube has laseretch lines around its circumference.
 8. The flip retrograde cutter ofclaim 1, wherein the shaft has a diameter of about 3.5 mm.